My app offers auto renewable subscriptions, I have couple of questions regarding how to model the subscriptions at server side, Is originalTransactionId will ever change for a subscription? Will it stay same in case of subscription upgrade/downgrade/crossgrade? If it changes on product change then how do i keep track that the subscription was a continuous subscription and not a new one? Is the webhook payload contains any identifier of which apple account purchase the subscription? I am having issues maintaining sync between the app account's current subscription and the local apple account's subscription, is there any doc regarding this? Will be really helpful